Lutron DI6400 is the third evolution of the line and their most recent release Insulation Tester. These units are economical and deliver performance levels to suit AS3000 wiring rules. With a large liquid crystal display and fast response, the DI-6400 is easy to use and reliable. It is powered by 8 AA batteries and there is an optional computer interface and PC software. With 4 test voltages and 4 ranges in each voltage - you get the reading you need in 4 seconds. Safety is assured with a large LOCK and TEST button.